1. Field of the Invention:
The present invention pertains generally to the drilling and completion of petroleum wells. More specifically, the invention pertains to a vertically movable, derrick-mounted driving apparatus for rotating a drill string and for manipulating pipe members being run into or removed from a well.
2. Brief Description of the Prior Art
In the conventional method of drilling wells, large internal combustion engines or other power sources are employed to rotate a rotary table set in the floor of a drilling derrick. Slidingly engaging a square hole in the rotary table is a square kelly member to which rotary motion is imparted by the table while the kelly is free to slide vertically therethrough. The lower end of the kelly is threadedly connected to the upper end of a string of drill pipe and the rotary motion is carried to a bit located at the lower end of the string.
As lengths of pipe are added to or removed from the drill string, it is necessary to employ auxiliary equipment such as wrenches, tongs, elevators, ropes, and chains to threadedly connect and disconnect the pipe members employed in the string. This technique, which is well known, is slow and extremely dangerous.
In U.S. Pat. Nos. 3,467,202; 3,744,697; 3,766,991; and 3,776,320 and in U.S. Pat. Application Ser. No. 418,065 filed Nov. 21, 1973 new and improved methods and apparatuses for drilling wells are disclosed in which the heavy rotary table, the chain drive connections, large internal combustion engines, tongs, spinning chains, manually set slips and other appurtenances of conventional well drilling equipment are eliminated. In these improved systems, a rotary power device, such as an electric motor, is supported from the traveling block of a drilling derrick for imparting rotary motion to the drill string. The rotary power device is equipped with a rotatable output shaft which may be provided with a threaded pin for connection to the upper end of a drill string.
U.S. Pat. No. 3,766,991 describes a connector device which may be connected to the output shaft of the power source to provide non-threaded engagement with the upper end of a pipe string. The connector includes a tubular housing adapted to coaxially receive the upper end of the pipe string and a set of pipe gripping shoes rockably mounted in the housing for angular movement into and out of gripping engagement with the upper end of the well pipe in accordance with the direction of angular movement of the housing relative to the pipe string. Thus, the pipe string may be rotated by the connector for drilling, or joints of pipe may be connected to and disconnected from the string as the string is run into or removed from the well.
U.S. Pat. No. 3,776,320 discloses an improved drive connector featuring a tubular housing having a longitudinal section removed therefrom to form a side opening through which a pipe member may be laterally placed in the housing. In many applications, this technique of encircling the pipe member with the connector may prove to be more convenient than the method of inserting the pipe member from the bottom of the connector, particularly where the pipe has an enlarged upset end.
U.S. Patent Application Ser. No. 477,028 filed June 6, 1974, discloses several methods for gripping pipe members in both side and bottom insertion elevators. Powered cocking cylinders also provide convenient lateral maneuvering of pipe members. A lost motion mechanism incorporated in the connector provides a jarring rotary impact to the elevator for breaking out pipe string joints.
In practice, the drive connector of the type herein described is massive and cumbersome. Therefore, the precise alignment of the elevator necessary for pipe manipulation may be a difficult operation. Also, the cam-operated gripping devices may be relatively sluggish and inefficient when applied to but a single pipe segment.